1. Field of the Invention
The invention relates to an apparatus for fixing the winding ends of a stator winding in a dynamoelectrical machine, in which the winding ends have inner and outer layers which are mechanically and electrically connected to each other at the axially outer end, consisting of an outer ring and an inner ring, means for connecting the two rings to each other, means for bracing the two rings and said winding ends and means for fastening the outer ring to the end face of the stator laminated core.
The invention makes reference in this respect to a prior art as emerges for example from German Offenlegungsschrift 1,613,125 or German Auslegeschrift 1,463,796.
2. Discussion of Background
The fastening of the winding ends of the stator windings (winding overhang) of turbo-generators presents certain problems due to the great demands to which these winding overhangs are subjected. These demands originate from the effects of electromagnetic forces, in particular in the event of a short-circuit, from vibrations and from differing thermal expansions of the stator bars in relation to the stator iron during operation.
In the case of the apparatus for fixing the winding ends of a stator winding in an electrical machine according to German Offenlegungsschrift 1,316,125, an outer ring externally hugs a part of the outer layers of the winding ends. An inner ring, which is independent of the outer ring, acts on the inner layers of the winding ends. To prevent mutual axial displacement of the two rings, devices designed as C-shaped clips are provided, which grip around the winding ends to connect the two clips. The two rings are screwed to axially running holders, which for their part are fastened to the end face of the stator laminated core.
In the case of the axially movable and radially fixed winding overhang holder for the stator winding of a turbo-generator according to German Auslegeschrift 1,463,796, the winding overhangs are spaced apart by means of wedges and intermediate pieces and held in place between two concentric insulating rings. In this arrangement, the outer insulating ring is fixed in relation to parts of the frame in radial direction by means of sliding wedges, which allow an axial displacement of the outer insulating ring upon thermal expansion of the winding overhang, and is connected to the stator frame by means of flexible parts.
The winding overhang holder according to U.S. Pat. Specification No. 4,800,314 corresponds by and large to that according to German Auslegeschrift 1,463,796, but uses only an outer ring. The winding overhang ends are wedged and bonded among themselves in groups and connected to this outer ring by means of bands.